The present invention relates generally to a needleless syringe for use in delivering particles into a target surface. More particularly, the invention is drawn to a needleless syringe system configured for delivery of particles initially disposed upon a first surface of a diaphragm using a shockwave force that is imparted upon a second, opposing surface of the diaphragm.
In commonly owned U.S. Pat. No. 5,630,796, a particle delivery system is described that entails the use of a needleless syringe. The syringe is used for delivering particles (powdered compounds and compositions) to skin, muscle, blood or lymph. The syringe can also be used in conjunction with surgery to deliver particles to organ surfaces, solid tumors and/or to surgical cavities (e.g., tumor beds or cavities after tumor resection).
The needleless syringe of U.S. Pat. No. 5,630,796 is typically constructed as an elongate tubular nozzle, having a rupturable membrane initially closing the passage through the nozzle adjacent to the upstream end of the nozzle. Particles, usually comprising a powdered therapeutic agent, are located adjacent to the membrane. The particles are delivered using an energizing means which applies a gaseous pressure to the upstream side of the membrane that is sufficient to burst the membrane, thereby producing a high velocity gas flow through the nozzle in which the particles are entrained.
Particle delivery using the above-described needleless syringe is typically carried out with particles having an approximate size that generally ranges between 0.1 and 250 xcexcm. For drug delivery, an optimal particle size is usually at least about 10 to 15 xcexcm (the size of a typical cell). For gene delivery, an optimal particle size is generally substantially smaller than 10 xcexcm. Particles larger than about 250 xcexcm can also be delivered from the device, with the upper limitation being the point at which the size of the particles would cause untoward damage to the target tissue. The actual distance which the delivered particles will penetrate depends upon particle size (e.g., the nominal particle diameter assuming a roughly spherical particle geometry), particle density, the initial velocity at which the particle impacts the target surface, and the density and kinematic viscosity of the target tissue (e.g., skin). In this regard, optimal particle densities for use in needleless injection generally range between about 0.1 and 25 g/cm3, preferably between about 0.5 and 2.0 g/cm3, and injection velocities generally range between about 100 and 3,000 m/sec.
In one embodiment of the invention, a needleless syringe is provided. The needleless syringe is capable of accelerating particles comprising a therapeutic agent across skin or mucosal tissue of a vertebrate subject. The syringe comprises, in operative combination, a body having a lumen extending therethrough. The lumen has an upstream terminus and a downstream terminus, and the upstream terminus of the lumen is interfaced with an energizing means such as a volume of a pressurized driving gas. The syringe further includes a diaphragm arranged adjacent to the downstream terminus of the lumen, wherein the diaphragm has an internal surface facing the lumen and an external surface facing outwardly from the syringe. The diaphragm is moveable between an initial position in which a concavity is provided on the external surface of the diaphragm, and a dynamic position in which the external surface of the diaphragm is substantially convex.
In certain aspects of the invention, the diaphragm is an eversible dome-shaped membrane that is comprised of a flexible polymeric material. In other aspects, the diaphragm is a bistable membrane that is moveable between an initial, inverted position and a dynamic, everted position. Particles comprising a therapeutic agent are generally housed within the concavity provided by the external surface of the diaphragm when in its initial position. The body of the needleless syringe can be configured as an elongate tubular structure with the diaphragm arranged over the downstream terminus of a lumen extending along the major axis of the tubular structure, or over an opening adjacent to the downstream terminus, which opening faces in a direction substantially perpendicular to the major axis of the tubular structure.
In another embodiment, a dome-shaped diaphragm for use with a needleless syringe is provided. The diaphragm has a concavity that sealably contains particles comprising a therapeutic agent.
In yet another embodiment of the invention, a needleless syringe is provided comprising a body having a lumen extending therethrough. The lumen has an upstream terminus and a downstream terminus, and the upstream terminus of the lumen is interfaced with an energizing means such as a volume of a pressurized driving gas. The syringe further includes a diaphragm arranged adjacent to the downstream terminus of the lumen, wherein the diaphragm has an internal surface facing the lumen and an external surface facing outwardly from the syringe. The diaphragm is moveable between an initial position in which a concavity is provided on the external surface of the diaphragm, and a dynamic position in which the external surface of the diaphragm is substantially convex. The diaphragm is characterized in that its external surface comprises one or more topographical features which selectively retain particles on the external surface of the diaphragm when in its initial, xe2x80x9cloadedxe2x80x9d position.
In a still further embodiment of the invention, a method for transdermal delivery of particles is provided. The method entails providing a needleless syringe according to the invention, wherein the syringe has a diaphragm with a concave surface and a convex surface, and particles are disposed on the concave surface of the diaphragm. A gaseous shock wave is released in a direction toward the convex surface of the diaphragm, wherein the shock wave provides sufficient motive force to impel the diaphragm to an everted position, thereby dislodging the particles from the diaphragm and accelerating them toward a target surface.
In certain aspects of the invention, the particles are accelerated toward the target surface in a direction substantially collinear with the direction of travel of the gaseous shock wave. In other aspects of the invention, the particles are accelerated toward the target surface in a direction transverse to the direction of travel of the gaseous shock wave.
These and other embodiments of the present invention will readily occur to those of ordinary skill in the art in view of the disclosure herein.